Strategies of myocardial protection for operation in chronic model of cyanotic heart disease

Abstract

Background. Cyanotic congenital hearts have an increased susceptibility to ischemia and subsequent reperfusion. The role of platelet-activating factor antagonism and mechanical neutrophil depletion with leukocyte-depleting filters for control of ischemia-reperfusion injury was assessed in corrective surgical procedures for cyanotic heart disease. Methods. A swine model of cyanotic heart disease was evaluated with three study groups: a control group; a group given a platelet-activating factor antagonist (PAFA group); and a group with leukocyte-depleting filtration (LDF group). The cyanotic model was created with a left atrial appendage–pulmonary artery fistula with peripheral banding through a left anterior thoracotomy in weanling swine. The experimental procedure was performed 5 to 7 weeks later when body weight was greater than 20 kg and oxygen saturation was 85% or less. The corrective procedure was performed through a median sternotomy on cardiopulmonary bypass with repair of the shunt. Myocardial protection was accomplished with hypothermic blood-crystalloid (4:1) cardioplegia; the period of ischemic arrest was 90 minutes. In the PAFA group, the platelet-activating factor antagonist CV-6209 was delivered intravenously 15 to 20 minutes before aortic cross-clamping. In the LDF group, Pall leukocyte-depleting filters were used in the CPB arterial line. Hemodynamic data were taken before operation and 10 and 30 minutes after CPB with impedance ventriculography. Results. There were four deaths in the control group within 30 minutes after CPB; all animals in the treated groups survived longer than 60 minutes ( p < 0.05). The ventricular assessment of end-systolic elastance revealed superior performance in the LDF group 30 minutes after CPB compared with the control group ( p < 0.05) (controls, 4.0 ± 9; PAFA group, 6.5 ± 3.7; and LDF group, 12.0 ± 4.6). Conclusions. Both leukocyte-depleting filters and platelet-activating factor antagonism provided myocardial protection, and the filters afforded superior postoperative myocardial contractility.